Improvement in casters



G. B. MUNN.

Improvement in Casters.

Patented July 16,1872.

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UNITED STATES GEORGE B. MUNN, OF NEW BRUNSWICK, NEW JERSEY.

IMPROVEMENT IN CASTERS.

Specification forming part of Letters Patent No. 128,972, dated July 16, 1872.

SPECIFICATION.

To all whom it may concern.-

Be it known that I, GEORGE B. MUNN, of New Brunswick, in the county of Middlesex and State of New Jersey, have invented a new and useful Improvement in Casters, of which the following is a description:

My invention relates to that class of casters in which rollers are interposed between the parts to diminish friction; and has for its object to secure an equal and uniform bearing for the revolving wheel table, and obviate the effects of that leverage which arises from the necessary position of the axis of the wheel outside of that of the revolving table, and also to insure the least friction of the working parts, together with a construction which is simple and renders the internal parts readily accessible 5 and it consists in the combination of a series of friction-rollers of ovoid shape, with a skeleton traversing frame hung upon a central axial stud and guide, and arranged within an annular case between the fixed frame and revolving part of the caster, as hereinafter set forth.

In the drawing, Figure l is a perspective view of my caster, of a form adapted to use on boxes, &c.; Fig. 2, a similar view, adapted to use on pianos and furniture; Fig. 3, a vertical sectional elevation; Fig. 4, a plan of the xed portion, containing the annular case, in-

verted, with the revolving table and wheel removed, showing the ovoid rollers, transverse frame, and axial stud; Fig. 5, a sectional perspective view of the annular case, showing the axial stud; Fig. 6, a perspective view of the traversing-frame, removed.

The part connecting with the piano-leg or furniture is formed with a cylindrical portion, B, preferably above the flange b, by which the caster is attached. Where the caster is intended for use on boxes, &c., it has a broad, horizontal, bearing-surface, C, inclosed on two sides by a rectangular ange, c, provided with screw-holes for securing the caster in place. The wheel D with its arms e e are of ordinary construction, the latter projecting from the revolving table E, which is secured within the annular chamber B, with its lower surface, preferably, on the same plane as that of the flange-b, being journaled on the axial stud f,

to which it is secured by the screw fi. The stud f projects downward centrally through the annular chamber, and forms the axis upon which both the revolving table E and the skeleton frame G revolve. This frame G is employed to keep the rollers J in proper position, each being inclosed by the vertical sidesV of the chambered arms g, in which they lic, and upon the remaining side by the inner vertical surface of the chamber B, and resting upon the revolvingtable E, while, in turn, the inner horizontal surface or roof of said chamber rests upon them, thus bringing the whole strain or Weight on the socket-piece A through the medium of the rollersJ, upon the revolving table E and wheel D. The effect of the axial stud as a journal to the revolving table E, in combination .with the rollers J J, is such that the weight and strain are made to act vertically and centrally upon the caster, avoiding all leverage and prying action between the parts, and consequently decreasing wear and liability to accident. This effect is aided and increased by the form of the rollers, which are of slightly curved or ovoid-shape, in longitudinal section, so that the extent of surface in contact between them and the top of the chamber B, the revolving table E, and the skeleton frame G, is reduced to the minimum degree. Their ends next the wall ofthe annular chamber are made conical or pointed at the center, which point, being in contact with the side of the chamber, serves as a spindle or axis on which the roller revolves, the centrifugal force imparted to the rollers during the turning of the table E tending constantly to keep said point in contact with the wall of the chamber.

The stud f is of importance in furnishing both an axis to the revolving table and skeleton frame, and in retaining and supporting all the parts together by means of the screw i. Without such provision the action between the'parts would be less smooth and uniform, and the friction, by being unequally distributed on the rollers J J, would be greater, besides which, friction would occur between the periphery of the table and the chamber, resulting from the inclination of the former due to the leverage of the arms e e.

The revolving table and wheel portion of the caster are connected with the fixed portion by a single screw, z', entering` the axial stud f, by removing which the parts are all separable for oiling, or other purposes.

What I claim is- The skeleton frame Gr, formed with the chambered-arms g g g g, in combination with the ovoid friction-rollers J, axial stud f, annular chamber B, and revolving' table E, arranged and operating substantially as and for the pur pose set forth.

In Witness whereof I have hereunto signed my name in the presence of two subscribing Witnesses.

Witnesses: GEO. B. MUNN.

J. H. VAIL, HENRY WHHNEY. 

